User manual

SANtools® S.M.A.R.T. Disk Monitor (SMARTMon-UX)228
SANTOOLS® is registered in US Patent and Trademark Office No 3,107,854 All rights reserved.
4 Frequenty Asked Questions
4.1 What are Sense Codes?
Sense data contains detailed information about error conditions. It is organized into major categories called sense
keys and sub categories called additional sense codes (ASC) and additional sense code qualifiers (ASCQ). The
combination of these data fields can finely convey detailed information about the error condition.
Whenever a command is sent to a SCSI device, the sense data is made available to the device driver.
The sense keys are generic and have the same meaning regardless of the type of device. For example, sense key #1
means to "Check Condition", but the command completed. Combined with the ASC and ASCQ bytes, the condition
check might actually translate into something like, "Fly Height Change Problem, Recommend Device
Replacement". Which would be the case if you had an IBM DGHS Ultrastar and received sense Code of 5d, qualifier
00, additional codes 02 25.
Your syslog file may have these types of messages in them, so in the event of a problem, you should inspect this file.
4.2 What is S.M.A.R.T. and How Does it Work?
S.M.A.R.T. is an acronym for Self-Monitoring, Analysis and Reporting Technology, an open standard for developing
disk drives and software systems that automatically monitor a disk drive's health and report potential problems.
Ideally, if a problem is reported, you have enough time to take proactive actions to prevent impending disk crashes.
A S.M.A.R.T. drive monitors the internal performance of the motors, media, heads, and electronics of the drive, while
our software monitors the overall reliability status of the drive. The reliability status is determined through the analysis
of the drive's internal performance level and the comparison of internal performance levels to predetermined threshold
limits.
How does S.M.A.R.T. Work?
Part of what makes the S.M.A.R.T. system possible is that disk drive reliability has been intensely studied for many
years. Manufacturers spend billions of dollars researching how vital areas of disk drives change over time and
operating environments. By analyzing this data, they can define performance thresholds, which correlate to imminent
failures.
SMART Disk Monitor turns on this capability, interacts with it, and reports these conditions to the system
administrator.
Mode Page 1C Settings
All SCSI, Fibre Channel, SSA, and SAS disks allow an application to configure the S.M.A.R.T. behavior by making
changes in mode page 1C. As these changes affect how the disk responds to I/Os when the disk triggers a SMART
condition, it is important that we share this with you along with our rationality for having things the way they are.
ANSI-Defi
ned
Field
Name
Description
SMARTMon-UX
Setting
Notes
PERF
Performance bit
0.
This is configurable
with -P option
Enable this for high-throughput i.e., video streaming systems.
The disk drive will prioritize application I/O over SMART
diagnostics.
EWASC
Enable Warning bit
1
If disk supports this bit, it will be set to 1, otherwise 0.
DEXCPT
Disable Exception bit
0
0 means to turn ON SMART, 1 means turn off SMART.
Use the -p flag to turn SMART off
MRIE
Method of Reporting
6
Setting MRIE to 6 is preferred, as a SMART alert will only be
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